[GitHub] [arrow-rs] bjchambers commented on a change in pull request #389: make slice work for nested types

[GitBox <gi...@apache.org>]

bjchambers commented on a change in pull request #389:
URL: https://github.com/apache/arrow-rs/pull/389#discussion_r668032570



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File path: arrow/src/array/array_struct.rs
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@@ -85,12 +85,7 @@ impl From<ArrayData> for StructArray {
     fn from(data: ArrayData) -> Self {
         let mut boxed_fields = vec![];
         for cd in data.child_data() {
-            let child_data = if data.offset() != 0 || data.len() != cd.len() {

Review comment:
       This seems to make sense -- my main interest was in getting the tests I added (concat on sliced struct arrays) to pass because I had run into problems with that. It seems like the tests are still here and passing, and it sounds like this may be more robust as well (addressing other issues I've hit when slicing `StructArray` such as the mentioned equality issues).
   
   For my own curiosity -- If I understand correctly, slicing the child data doesn't actually copy the data, but just creates a reference to the same data with different offsets, so this shouldn't affect performance significantly, correct?




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